Features
 8 x 18bit differential inputs
 Control via the Raspberry Pi I2C port
 Stack up to 4 ADC Differential Pi boards on a single Raspberry Pi
 Jumper selectable I2C addresses
 Buffered 5V I2C port
 Based on the MCP3424 from Microchip Technologies Inc
 Input voltage range of ±2.048V
 Onboard 2.048V reference voltage (Accuracy ± 0.05%, Drift: 15 ppm/°C)
 Onboard Programmable Gain Amplifier (PGA): Gains of 1, 2, 4 or 8
 Programmable Data Rate Options:
 3.75 SPS (18 bits)
 15 SPS (16 bits)
 60 SPS (14 bits)
 240 SPS (12 bits)
 OneShot or Continuous Conversion Options
The ADC Differential Pi is an 8channel, 18bit analogue to digital converter designed to work with the Raspberry Pi and other compatible singleboard computers. The ADC Differential Pi is based on two Microchip MCP3424 A/D converters, each containing 4 analogue inputs. The MCP3424 is a deltasigma A/D converter with low noise differential inputs.
Not sure which ADC you need? Check our Analogue to Digital Buyers guide to compare our ADC expansion boards.
We designed the ADC Differential Pi as a companion for our ADC Pi. Unlike the ADC Pi, the ADC Differential Pi does not include any voltage dividers, so the inputs can measure a differential voltage range of ±2.048V. This is useful for measuring inputs below ±2.048V or using a voltage divider to measure higher voltages.
The ADC Differential Pi is powered through the host Raspberry Pi using the GPIO port. Extended pins on the GPIO connector allow you to stack the ADC Differential Pi and other expansion boards.
The two MCP3424 A/D converters communicate via i2c to the host Raspberry Pi, giving you eight analogue inputs. A logic level converter is included on the ADC Pi Plus board, giving you a buffered 5V I2C port, making it easy to add other I2C devices which operate at 5 volts without damaging the Raspberry Pi 3.3 volt I2C port. The i2c buffer uses Nchannel MOSFETs with a maximum drain current of 100mA.
The I2C address bits are selectable using the onboard jumpers. The MCP3424 supports up to 8 different I2C addresses, so with two A/D converters on each ADC Differential Pi, you can stack up to 4 ADC Differential Pi boards on a single Raspberry Pi, giving you 32 ADC inputs.
The MCP3424 contains an onboard 2.048V reference voltage with an input range of ±2.048V differentially (fullscale range of 4.096V/PGA). A programmable Gain Amplifier gives the user a selectable gain of x1, x2, x4 or x8 before the analogue to digital conversion occurs.
The data rate for analogue to digital conversions is 3.75 (18bit), 15 (16bit), 60 (14bit) or 240 (12bit) samples per second. Data rate and resolution can be configured within the software using the I2C interface.
Our knowledge base article, ADC Sample Rate Comparison, has more detailed sample information and test scripts to compare the different MCP2424 ADC chip bit and sample rates.
Unused inputs should be tied to ground.
Legacy Delta Sigma Pi Versions
See our KB article for previous versions of this board.
Code Libraries and Demos
This expansion board has Python, MicroPython, C, C++, Node.JS, .Net Core, Arduino and Home Assistant libraries available to get you started with your next project. You can download all of the libraries from GitHub at:
https://github.com/abelectronicsuk/ or click on the logos below for your selected programming language.
Compatibility
We have tested the ADC Differential Pi on the following platforms.
Model 
Status 
Raspberry Pi Pico series 

Raspberry Pi Model A / B 

Raspberry Pi 1 Model A+ / B+ 

Raspberry Pi 2 Model B 

Raspberry Pi 3 Model A+ / B / B+ 

Raspberry Pi 4 Model B 

Raspberry Pi 5 

Raspberry Pi Zero 

Raspberry Pi Zero W / Zero 2 W 

Raspberry Pi Compute Module 4 IO Board 

Raspberry Pi 400 

Orange Pi 

Asus Tinker Board 

Odroid 
